JPWO2019225566A1 - Optical integrated circuits and integrated circuits - Google Patents

Abstract

The optical integrated circuit (104) is formed on the side of the optical waveguide (203 or 204) and the optical waveguide (203 or 204), converts an electric signal into an optical signal, and converts the optical signal into an optical waveguide (204). ), Or a laser diode (202) or a photodiode (201) that converts an optical signal transmitted through an optical waveguide (203) into an electric signal, and the laser diode (202) or the photodiode (201). A circular main resonator (401) surrounded by a photonic crystal structure and a sub-resonator (402) formed in the vicinity of the main resonator (401) and surrounded by a photonic crystal structure. Have.

Description

The present disclosure relates to an optical integrated circuit including a photodiode having a resonator surrounded by a photonic crystal structure.

Patent Document 1 and Patent Document 2 describe an optical integrated circuit having a resonator surrounded by a photonic crystal structure. For example, in the optical integrated circuits described in Patent Document 1 and Patent Document 2, a plurality of resonators are formed on the side of the optical waveguide, and optical signals generated by the plurality of resonators are output to the optical waveguide.

Japanese Unexamined Patent Publication No. 2007-194301 JP-A-2009-239260

In such an optical integrated circuit, it is preferable that the optical signal output from the resonator can be transmitted in one direction of the optical waveguide, or the optical signal transmitted from one direction of the optical waveguide can be converted into an electric signal.

Therefore, the present disclosure provides an optical integrated circuit or an integrated circuit capable of increasing the ratio of optical signals output in one direction of an optical waveguide or the ratio of optical signals transmitted from one direction input to a resonator. With the goal.

The optical integrated circuit according to one aspect of the present disclosure is formed on the side of the optical waveguide and the optical waveguide, converts an electric signal into an optical signal, and outputs the optical signal to the optical waveguide, or A light diode that converts an optical signal transmitted through the optical waveguide into an electric signal is provided, and the optical diode is formed in the vicinity of a circular main resonator surrounded by a photonic crystal structure and the main resonator. And has a sub-resonator surrounded by a photonic crystal structure.

The present disclosure can provide an optical integrated circuit or an integrated circuit capable of increasing the ratio of optical signals output in one direction of an optical waveguide or the ratio of optical signals transmitted from one direction input to a resonator.

FIG. 1 is a diagram showing a configuration of an integrated circuit according to an embodiment. FIG. 2 is a perspective view of the optical integrated circuit according to the embodiment. FIG. 3 is a diagram showing a state of connection between the optical integrated circuit and the optical waveguide according to the embodiment. FIG. 4 is a diagram showing a state of connection between the optical integrated circuit and the optical fiber according to the embodiment. FIG. 5 is a plan view of the laser diode and the optical waveguide according to the embodiment. FIG. 6 is a plan view of the laser diode and the optical waveguide according to the embodiment. FIG. 7 is a diagram showing simulation conditions for changing the position of the sub-resonator according to the embodiment. FIG. 8 is a diagram showing a left-right ratio with respect to the position of the sub-resonator according to the embodiment. FIG. 9 is a diagram showing the width of the sub-resonator according to the embodiment. FIG. 10 is an enlarged view of the periphery of the optical waveguide according to the embodiment. FIG. 11 is a diagram showing the coupling efficiency with respect to the shift amount of the side vacancies of the optical waveguide according to the embodiment. FIG. 12 is a plan view of the laser diode and the optical waveguide according to the modified example of the embodiment. FIG. 13 is a diagram showing the coupling efficiency with respect to the shift amount of the side vacancies of the optical waveguide according to the modified example of the embodiment.

(Knowledge on which this disclosure was based)
The development of the information-oriented society in recent years has been remarkable. This is largely due to the development of software. On the other hand, the development of hardware has already reached a point close to the physical limit, and there is little room for growth. For example, the clock speed of semiconductor CPU chips, which are the core of information processing, has hardly changed in the last 10 years. Information transmission in the chip is performed by metal wiring, and signal delay occurs due to miniaturization of wiring. When the clock speed is increased, the chip itself generates heat and the power consumption is greatly increased. Currently, a clock speed of about 3 GHz is a compromise. On the other hand, in order to improve the performance of the CPU chip, a plurality of parts called cores for performing information processing are provided, and parallel processing is performed by the plurality of cores.

The size of the CPU chip is several centimeters square, and about 10 billion transistors are formed in the CPU chip. If they are operated at the same clock speed, problems of heat generation and power consumption will occur. As a solution to this, there is a method of performing information processing with a plurality of small cores.

Information transmission between cores is important for parallel processing in multiple cores. Since all information transmission is performed by metal wiring inside the current CPU chip, problems of heat generation and power consumption in this metal wiring occur.

In the CPU chip of the present disclosure, optical wiring is used for information transmission between cores. Conventional optical transmission technology is used for relatively long-distance information transmission, and the size of the optical transmission module is large. Therefore, it is difficult to incorporate such a technique into a chip. This disclosure describes a microscopic optical module that makes this possible.

Further, the optical modules described in Patent Document 1 and Patent Document 2 have the following problems. In these optical modules, an optical diode having a resonator is formed on the side of the optical waveguide. The optical signal generated by the photodiode is output to the optical waveguide. Here, the optical signal output to the optical waveguide needs to be transmitted in either direction of the optical waveguide. However, in the prior art, the optical signal is transmitted in both directions. For example, when transmitting an optical signal to the left, the optical signal transmitted to the right is reflected in a phase adjustment region at the end of the optical waveguide, and this reflected wave is transmitted to the left. Therefore, by adjusting the phase of the optical signal output from the resonator to the left and the phase of the reflected wave to be in phase, it is possible to suppress the attenuation of the optical signal. However, when a plurality of resonators having different wavelengths are provided on the side of one optical waveguide, there is a problem that it is difficult to adjust the phases of all the optical signals of these plurality of resonators. This can lead to errors in optical transmission.

The optical integrated circuit according to one aspect of the present disclosure is formed on the side of the optical waveguide and the optical waveguide, converts an electric signal into an optical signal, and outputs the optical signal to the optical waveguide, or A light diode that converts an optical signal transmitted through the optical waveguide into an electric signal is provided, and the optical diode is formed in the vicinity of a circular main resonator surrounded by a photonic crystal structure and the main resonator. And has a sub-resonator surrounded by a photonic crystal structure.

According to this, by providing the sub-resonator, the ratio of the optical signal output in one direction of the optical waveguide or the ratio of the optical signal transmitted from one direction input to the resonator can be increased.

For example, the sub-resonator may be formed asymmetrically with respect to the clockwise and counter-clockwise optical signals in the main resonator.

For example, the sub-resonator may have different effects on the clockwise and counterclockwise optical signals in the main resonator.

For example, the sub-resonator may be formed other than between the main resonator and the optical waveguide.

According to this, it is possible to suppress that the sub-resonator interferes with the optical coupling between the main resonator and the optical waveguide.

For example, the main resonator and the sub-resonator may be adjacent to each other.

According to this, the ratio of the optical signal output in one direction of the optical waveguide or the ratio of the optical signal transmitted from one direction input to the resonator can be further increased.

For example, the sub-resonator may be formed by removing pores having a photonic crystal structure of 1 or more and 3 or less.

According to this, the ratio of the optical signal output in one direction of the optical waveguide or the ratio of the optical signal transmitted from one direction input to the resonator can be further increased.

For example, the optical waveguide is surrounded on both sides by a photonic crystal structure, and the distance between the photonic crystal structures on both sides of the optical waveguide is a photonic crystal structure other than both sides of the optical waveguide. It may be wider than the interval of.

According to this, the coupling efficiency between the main resonator and the optical waveguide can be improved.

For example, the optical integrated circuit includes a plurality of optical diodes including the optical diode, and the plurality of optical diodes are formed on the side of the optical waveguide, and (1) electric signals have different wavelengths from each other. It is converted into an optical signal and the optical signal is output to the optical waveguide, or (2) optical signals having different wavelengths transmitted through the optical waveguide are converted into an electric signal, and the optical waveguide is in the signal transmission direction. It may have a groove formed along the.

According to this, by providing a groove in the optical waveguide, it is possible to improve the coupling efficiency between a plurality of photodiodes having different wavelengths and the optical waveguide.

The integrated circuit according to one aspect of the present disclosure is an integrated circuit that transmits signals via electricity and light, and includes the optical integrated circuit.

The integrated circuit according to one aspect of the present disclosure includes a plurality of cores and the optical integrated circuit that transmits signals between the plurality of cores.

According to this, it is possible to realize high performance of an integrated circuit having a plurality of cores.

For example, the integrated circuit may include a plurality of blocks, each containing a plurality of the cores, and the optical integrated circuit may transmit signals between the plurality of blocks.

According to this, by using the electric wiring in the block and the optical wiring between the blocks, it is possible to suppress the increase of the optical wiring and realize the high performance of the integrated circuit.

It should be noted that these comprehensive or specific aspects may be realized by a system, a method, or an integrated circuit, or may be realized by any combination of a system, a method, and an integrated circuit.

Hereinafter, embodiments will be specifically described with reference to the drawings. It should be noted that all of the embodiments described below show a specific example of the present disclosure. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, etc. shown in the following embodiments are examples, and are not intended to limit the present disclosure. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept are described as arbitrary components.

(Embodiment)
Currently, the number of cores of commercially available CPUs is 10 or less, but there is a demand for an increase of nearly an order of magnitude in the near future. Specifically, a CPU having 9 × 9 = 81 cores is manufactured. Nearly 10,000 optical waveguides are required to connect all 81 cores with optical waveguides. Since the optical waveguide has almost no loss and no signal delay occurs when it is used within the size of the CPU chip, it is not necessary to consider the distance between the cores in the design. However, the optical waveguide is larger in size than the electrical wiring. Further, when the optical waveguide is grade-separated, the production thereof is not easy and the cost is high. A practical configuration is a hybrid of electrical wiring and optical wiring.

FIG. 1 is a diagram showing a configuration of an integrated circuit 100 according to the present embodiment. Note that FIG. 1 is a schematic diagram, and the size ratio of each component does not always match the actual one. The integrated circuit 100 transmits signals via electricity and light. As shown in FIG. 1, the integrated circuit 100 is, for example, a semiconductor chip and functions as a CPU. The integrated circuit 100 includes nine blocks 101 of 3 × 3. Each block 101 contains 9 cores 102 (processor cores) of 3 × 3. That is, the integrated circuit 100 includes 81 cores 102 of 9 × 9. The core 102 does not have to be a processor core, and may be an arbitrary processing circuit.

Information transmission between a plurality of cores 102 included in one block 101 is performed by electrical wiring. Optical wiring is used for information transmission between the plurality of blocks 101 and information transmission between the integrated circuit 100 and the outside.

Specifically, each block 101 includes one port 103. The port 103 includes a part of the core 102 and four optical integrated circuits 104 (optical modules). The port 103 transmits a signal between the blocks 101 via the optical waveguide 105, or transmits a signal between the block 101 and the outside via the optical fiber 106. For example, of the nine cores 102 included in one block 101, the central core 102 functions as a core dedicated to communication and transmits an electric signal between the other eight cores 102 and the port 103. Do. For example, the block 101 is about 1 cm square, and the core 102 is about 3 mm square. The port 103 is about 1 mm square. That is, for example, the size of the port 103 is smaller than the size of the core 102. The size of the port 103 may be larger than the size of the core 102. Further, a part of the central core 102 may function as a port 103, or a part of each of the nine cores 102 may function as a port 103 without providing a core dedicated to communication.

The optical integrated circuit 104 transmits signals between the plurality of ports 103. Specifically, the optical integrated circuit 104 transmits signals between the plurality of blocks 101.

More specifically, the four optical integrated circuits 104 transmit optical signals to other blocks 101 adjacent to the four sides or to the outside. Specifically, the optical waveguide 105 is used for transmitting the optical signal between the blocks 101, and the optical fiber 106 is used for transmitting the optical signal between the block 101 and the outside.

The number and size of the blocks 101 and the core 102 are examples, and any number or size of the blocks 101 and the core 102 may be used.

Further, according to the configuration shown in FIG. 1, a network can be constructed in the CPU. As a result, even if any of the optical integrated circuits 104 fails, information can be transmitted via a detour route. Therefore, it is possible to suppress a decrease in CPU performance when the optical integrated circuit 104 fails.

FIG. 2 is a perspective view showing the configuration of the optical integrated circuit 104. The optical integrated circuit 104 shown in FIG. 2 is a semiconductor integrated circuit that mutually converts an optical signal including an optical signal having a plurality of wavelengths and an electric signal, and is a plurality of photodiodes (PD) formed on the semiconductor substrate 205. It includes 201a to 201c, a plurality of laser diodes (LDs) 202a to 202c, an optical waveguide 203 for input, and an optical waveguide 204 for output. When the plurality of photodiodes 201a to 201c are not particularly distinguished, they are referred to as photodiodes 201, and when the plurality of laser diodes 202a to 202c are not particularly distinguished, they are referred to as laser diodes 202.

The optical waveguide 203 for input is an optical waveguide that transmits an input optical signal 208 input from the outside. The optical waveguide 204 for output is an optical waveguide that transmits an output optical signal 209 to be output to the outside.

The plurality of photodiodes 201 are formed on the side of the optical waveguide 203 and are optically connected to the optical waveguide 203. The plurality of photodiodes 201 are optical diodes that convert an input optical signal 208 transmitted by the optical waveguide 203 into an electric signal. Each photodiode 201 includes an electrode 206. Each photodiode 201 converts light of different wavelengths contained in the input optical signal 208 into an electric signal. For example, the wavelength of the optical signal converted by the photodiode 201a into an electric signal is 1290 nm, the wavelength of the optical signal converted by the photodiode 201b into an electric signal is 1300 nm, and the wavelength of the optical signal converted by the photodiode 201c into an electric signal is The wavelength is 1310 nm.

The plurality of laser diodes 202 are formed on the side of the optical waveguide 204 and are optically connected to the optical waveguide 204. The plurality of laser diodes 202 are optical diodes that convert an electric signal into an output optical signal 209 and output it to the optical waveguide 204. Each laser diode 202 includes an electrode 206. Each laser diode 202 converts an electrical signal into an optical signal of a different wavelength. For example, the wavelength of the optical signal output by the laser diode 202a is 1290 nm, the wavelength of the optical signal output by the laser diode 202b is 1300 nm, and the wavelength of the optical signal output by the laser diode 202c is 1310 nm.

FIG. 3 is a diagram schematically showing a state of connection between the optical integrated circuit 104 and the optical waveguide 105. As shown in FIG. 3, the IC 302, the electrode 303, and the wiring 304 are formed on the substrate 301. The substrate 301 is, for example, a Si substrate.

The IC 302 is an IC that amplifies and processes an electric signal output by the photodiode 201 of the optical integrated circuit 104 and supplies the electric signal to the laser diode 202 of the optical integrated circuit 104. Here, the optical integrated circuit 104, the IC 302, the electrode 303, and the wiring 304 are included in the port 103 shown in FIG. The IC 302 is, for example, a part of the core 102.

The optical integrated circuit 104 shown in FIG. 2 is turned upside down, and the electrode 303, each photodiode 201 of the optical integrated circuit 104, and the electrode 206 of each laser diode 202 are flip-chip bonded using solder bumps. Further, the electrode 303 and the IC 302 are connected via the wiring 304. As a result, the optical integrated circuit 104 and the IC 302 are connected. Further, the optical waveguide 105 and the optical waveguides 203 and 204 of the optical integrated circuit 104 are connected.

FIG. 4 is a diagram schematically showing a state of connection between the optical integrated circuit 104 and the optical fiber 106. The connection relationship between the substrate 301 and the optical integrated circuit 104 is the same as in FIG.

The optical fiber 106 is housed in a V-shaped groove formed in the substrate 301. The optical fiber 106 and the optical waveguides 203 and 204 of the optical integrated circuit 104 are connected.

Since the optical integrated circuit 104 in the present embodiment has a simple planar structure, it can be easily integrated as shown in FIGS. 3 and 4. Further, using the same optical integrated circuit 104, it is possible to fabricate the optical wiring between the blocks 101 and the outside of the chip by the same method. As a result, it is possible to reduce the cost and improve the life of the chip.

FIG. 5 is a top view of the laser diode 202 and the optical waveguide 204 shown in FIG. As shown in FIG. 5, the laser diode 202 includes a main resonator 401, a sub-resonator 402, and an electrode 206.

The main resonator 401, the sub-resonator 402, and the optical waveguide 204 are formed in a two-dimensional photonic crystal structure. That is, the main resonator 401, the sub-resonator 402, and the optical waveguide 204 are surrounded by a two-dimensional photonic crystal structure. The photonic crystal structure has a refractive index periodic structure formed by arranging the photonic crystal structures at a predetermined period, and specifically, the pores are arranged in a semiconductor in a two-dimensional triangular lattice pattern. For example, the lattice constant (lattice spacing) a of the photonic crystal structure is 340 nm, and the radius r of the pores is 0.3a. Note that these values are examples, and are not limited to these values. In addition, the values described below are all examples and are not limited thereto.

Light cannot exist in the region of the two-dimensional photonic crystal structure, and light can exist only in the part called the defect whose arrangement is disturbed. Therefore, when a linear defect is formed in the two-dimensional photonic crystal structure, light can penetrate into this portion and functions as an optical waveguide. When a defect that resonates light of a specific wavelength is placed in the vicinity of this optical waveguide, it functions as a resonator. Further, the wavelength of the resonating light is determined according to the shape and size of the resonator. As a result, optical signals having different wavelengths can be emitted from a common optical waveguide.

The main resonator 401 is circular and is optically connected to the optical waveguide 204. As for the cross-sectional structure and material of the laser diode 202, for example, the same structure as in Patent Document 1 or Patent Document 2 can be used. Further, in the present specification, the main resonator 401 is defined as a region including a region in which no vacancies are formed and a vacancies for one circumference surrounding the region. Similarly, a sub-resonator 402 is defined as a region including a region in which no vacancies are formed and a vacancies for one circumference surrounding the region.

An electrode 206 of the laser diode 202 is formed above the main resonator 401. An optical signal is generated according to the electric signal applied to the electrode 206 and output to the optical waveguide 204. The shape of the electrode 206 may be a shape that covers the entire main resonator 401 when viewed from above, and does not have to be the same shape as the main resonator 401. For example, the size of the electrode 206 is larger than the size of the main resonator 401 in order to align with the electrode 303 connected to the IC 302. For example, the radius R of the main resonator 401 is about 1 μm, and the length of one side of the electrode 206 is about 5 μm to 10 μm.

Further, as described above, the electrode 206 is flip-chip bonded to the electrode 303 by using a solder bump. At this time, if the bonding using the solder bump is performed on the upper part of the main resonator 401, the characteristics of the main resonator 401 may be deteriorated. Therefore, it is preferable that the electrode 206 has a shape and a size that can be bonded using a solder bump in a region other than the upper portion of the main resonator 401.

The sub-resonator 402 is smaller than the main resonator 401 and is formed in the vicinity of the main resonator 401. For example, as shown in FIG. 5, the electrode 206 is formed on the upper part of the sub-resonator 402. Here, the main resonator 401 and the electrode 206 are electrically connected, but the sub-resonator 402 and the electrode 206 are not electrically connected. Specifically, the core layer of the main resonator 401 is electrically connected to the electrode 206 via a conductive clad layer formed above the core layer. On the other hand, a non-conductive clad layer is formed above the core layer of the sub-resonator 402. As a result, the core layer of the sub-resonator 402 and the electrode 206 are not electrically connected. The electrode 206 may not be formed on the sub-resonator 402.

Although detailed description of the configuration of the photodiode 201 is omitted, for example, a structure similar to that of Patent Document 1 or Patent Document 2 can be used. Alternatively, as the photodiode 201 and the optical waveguide 203, the same configurations as those of the main resonator 401 and the optical waveguide 204 of the laser diode 202 may be used. That is, it is preferable that the photodiode 201 also includes the sub-resonator 402.

In the following, first, the operation of the main resonator 401 in the absence of the sub-resonator 402 will be described. The light generated in the circular main resonator 401 has the property of wanting to travel straight. Since light cannot enter the photonic crystal structure in which the pores are arranged two-dimensionally, the light orbits the outermost circumference of the main resonator 401. Since the main resonator 401 is surrounded by 18 holes, only a wave having 9 wavelengths exists stably as a standing wave. This standing wave is also a combination of clockwise (clockwise) and counterclockwise (counterclockwise) orbital waves. The clockwise orbiting wave is photocoupled to the optical waveguide 204 above the main resonator 401 in FIG. 5, and is emitted to the right of the optical waveguide 204 in the figure. On the other hand, the counterclockwise orbital wave is emitted to the left of the optical waveguide 204. Since the clockwise and counterclockwise light paths are exactly the same, the laser gain is also the same, and the optical waveguide 204 emits light of the same intensity on the left and right.

Here, the optical signal may be emitted to the left of the optical waveguide 204, and does not need to be emitted to the right. The optical signal transmitted in the right direction is reflected in the phase adjustment region at the right end of the optical waveguide 204 shown in FIG. 2, and the reflected wave is transmitted in the left direction. Therefore, by adjusting the position of the phase adjustment region so that the phase of the optical signal output to the left from the resonator and the phase of this reflected wave are in phase, the optical signal is suppressed from being attenuated. it can. As shown in FIG. 2, when a plurality of laser diodes 202 having different wavelengths are provided on the side of one optical waveguide 204, the phases of all the optical signals of the plurality of laser diodes 202 can be adjusted. There is a problem that it is difficult.

In the present embodiment, the sub-resonator 402 is provided to reduce the optical signal emitted to the right. This principle will be described below.

The counterclockwise light travels around the outer circumference of the main resonator 401 in the order of 11 o'clock, 10 o'clock, 9 o'clock, 8 o'clock, 7 o'clock, 6 o'clock, and 5 o'clock, and is not affected by the sub-resonator 402. The laser oscillates with the same gain as when there is no 402. On the other hand, the clockwise light travels around the outer circumference of the main resonator 401 at 1 o'clock, 2 o'clock, 3 o'clock, 4 o'clock and 5 o'clock, and at 6 o'clock, a part of the light having a straight traveling property is sub-resonant. Enter the vessel 402. The light that has entered the sub-resonator 402 is reflected in the sub-resonator 402 and returns to the main resonator 401 again. Since the reflected light travels counterclockwise, it affects the clockwise orbital wave, and the clockwise laser beam is significantly weakened.

Even if the length of the sub-resonator 402 (the size in the left-right direction in FIG. 5) was changed, there was almost no effect on the degree to which the clockwise light was reduced. In other words, the reason why the clockwise light is weakened is not because the phases of the traveling wave and the reflected wave are opposite to each other and cancel each other out, but because the phases of the reflected wave and the traveling wave are different, the gain of laser oscillation decreases. It is assumed that.

Further, in FIG. 5, the sub-resonator 402 is formed by not forming two holes, but even one hole functions as the sub-resonator 402. Further, in order to allow a large amount of clockwise light to enter the sub-resonator 402, the hole at the right end of the sub-resonator 402 is shifted from the original position of the triangular lattice to a position slightly closer to the main resonator 401. Similarly, the width of the sub-resonator 402 (the size in the vertical direction in FIG. 5) is slightly narrowed.

In the circular main resonator 401 with the sub-resonator 402 shown in FIG. 5, counterclockwise laser light is mainly generated, so that in the optical waveguide 204, the light traveling to the left is mainly generated. The positional relationship between the main resonator 401 and the optical waveguide 204 is designed as shown in FIG. 5 in order to make the optical coupling efficiency of the main resonator 401 and the optical waveguide 204 about 30%.

FIG. 6 is a diagram showing an example when two resonators are arranged on both sides of the optical waveguide 204. As shown in FIG. 6, the main resonator 401a and the sub-resonator 402a are formed on the lower side of the optical waveguide 204, and the main resonator 401b and the sub-resonator 402b are formed on the upper side of the optical waveguide 204.

Further, in FIG. 6, the sub-resonator 402a is formed by not forming one hole. Further, the sub-resonator 402a is located at a position rotated 60 degrees clockwise with respect to the sub-resonator 402 shown in FIG. In this case as well, as in the case of FIG. 5, the counterclockwise laser beam is mainly used, and the laser beam is emitted from the left side of the optical waveguide 204.

Further, the radius R2 of the main resonator 401b is slightly larger than the radius R1 of the main resonator 401a. Here, the length of the circumference where the standing wave exists is proportional to the radius R. Further, also in the main resonator 401b, as in the case of the main resonator 401a, only standing waves having nine wavelengths are stably present. Therefore, the wavelength of the main resonator 401b is slightly longer than the wavelength of the main resonator 401a. As described above, the output wavelengths of the main resonator 401a and the main resonator 401b are different.

Further, the basic design of the main resonator 401a and the sub-resonator 402a and the main resonator 401b and the sub-resonator 402b is vertically symmetrical with the optical waveguide 204 as the axis. That is, in the main resonator 401b, the clockwise laser beam is mainly used, and the optical signal is emitted from the left side of the optical waveguide 204.

By repeating the structure of FIG. 6, a wavelength division multiplexing optical module as shown in FIG. 2 can be manufactured. Here, since the size of the main resonator 401 is as small as 2 μm, for example, the size of the optical integrated circuit 104 is also very small, about 100 μm square. As a result, the port 103 can be realized with a size of about 1 mm square. As a result, it is possible to realize an integrated circuit 100 using optical wiring while suppressing an increase in size in a CPU chip having a size of about 3 cm square.

Although the configuration of the laser diode 202 has been mainly described here, by using the same configuration for the photodiode 201, the proportion of the optical signal transmitted from one direction input to the resonator is increased. The effect of being able to be realized can be realized.

As described above, the optical wiring can be introduced into the CPU chip and used for information transmission between cores. This improves the performance of the CPU by one to two orders of magnitude. The impact of this disclosure is enormous in the information-oriented society.

Further, the small size of the optical module (optical integrated circuit 104) is directly linked to the price reduction of the optical module. The smaller the module size, the more modules can be manufactured from one wafer, so the unit price of the optical module decreases. Further, the flip chip bonding shown in FIGS. 3 and 4 can be automated by using an infrared camera. Therefore, it is possible to realize the optical wiring in the chip while suppressing the price increase of the chip.

Further, in order to perform wavelength division multiplexing of light as in the present embodiment, the wavelength of each light diode must be within the allowable range of the design value. Generally, the wavelength of the optical diode is affected by the environmental temperature, so it is necessary to keep the temperature of the optical module constant (for example, 50 ° C.) by using a thermoelectric element or the like. Since the optical module 104 according to the present embodiment is very small, the power consumption of the thermoelectric element is very small, and the responsiveness to a change in the environmental temperature is also excellent. This temperature control mechanism is a part of the function required for the port 103.

The details of the sub-resonator 402 will be described below. As described above, the sub-resonator 402 is arranged so as to be optically coupled to one of the clockwise light and the counterclockwise light of the main resonator 401 and not to be optically coupled to the other. In other words, the sub-resonator 402 is arranged so that the optical coupling between the clockwise light and the counter-clockwise light of the main resonator 401 is stronger (or weaker) than the optical coupling with the other. That is, the sub-resonator 402 is formed asymmetrically with respect to the clockwise and counter-clockwise optical signals in the main resonator 401. Further, the sub-resonator 402 has different effects on the clockwise optical signal and the counterclockwise optical signal in the main resonator 401.

Further, it is preferable that the sub-resonator 402 is formed on the side opposite to the optical waveguide 204 of the main resonator 401. For example, in FIG. 5, the center (or upper end) of the sub-resonator 402 passes through the center of the main resonator 401 and is located below the line parallel to the optical waveguide 204. That is, the sub-resonator 402 is not formed between the main resonator 401 and the optical waveguide 404. In other words, the sub-resonator 402 is formed other than between the main resonator 401 and the optical waveguide 404. As a result, it is possible to prevent the sub-resonator 402 from inhibiting the optical coupling between the main resonator 401 and the optical waveguide 204.

Further, the main resonator 401 and the sub-resonator 402 may be adjacent to each other. Hereinafter, the simulation results when the distance between the sub-resonator 402 and the main resonator 401 is changed will be described. FIG. 7 is a diagram showing the conditions of the simulation. FIG. 8 is a diagram showing a simulation result when the position x of the defect of the sub-resonator 402 is changed as shown in FIG. 7. The length of the defect is one hole. The vertical axis of the graph shown in FIG. 8 indicates the ratio of the energy of the optical signal output in the right direction and the left direction (hereinafter referred to as the left-right ratio), and the higher the value, the more the energy of the optical signal in the desired direction. Is high (the energy of the optical signal in the unnecessary direction is low).

As shown in FIG. 8, when the main resonator 401 and the sub-resonator 402 are adjacent to each other (x = 1), the left-right ratio becomes the highest. Further, when x = 0, the left-right ratio is reduced. It is considered that this is because the sub-resonator 402 affects both clockwise and counterclockwise light.

Further, as shown in FIG. 9, when the defect length d (the number of holes to be removed) of the sub-resonator 402 is changed, the left-right ratio becomes high when the number of holes to be removed is 1 to 3. Moreover, there was no change in the left-right ratio during this period. On the other hand, it was found that the left-right ratio decreases when the number of pores to be removed is 4 or more. Therefore, it is preferable that the sub-resonator 402 is formed by removing the pores of 1 or more and 3 or less of the photonic crystal structure.

Further, in the present embodiment, the distance between the holes on both sides of the optical waveguide 204 is made wider than the distance a between the other holes. Thereby, the coupling efficiency of the optical coupling between the main resonator 401 and the optical waveguide 204 (hereinafter, also simply referred to as “coupling efficiency”) can be improved.

FIG. 10 is an enlarged view of the area 403 of FIG. In FIG. 10, the broken line holes indicate the holes arranged at intervals a like the other holes. As shown in FIG. 10, the holes on both sides of the optical waveguide 204 are shifted to the optical waveguide 204 side by −Δs. That is, the distance between the holes on both sides of the optical waveguide 204 is wider than the distance a between the other holes. In addition, Δs is positive in the direction away from the optical waveguide 204.

FIG. 11 is a diagram showing a simulation result of the coupling efficiency with respect to Δs / a. As shown in FIG. 11, the coupling efficiency can be improved by appropriately setting Δs.

Further, as shown in FIG. 11, by changing the radius R of the main resonator 401, that is, by changing the wavelength, an appropriate value of Δs changes. As a result, when a plurality of laser diodes 202 having different wavelengths are provided for one optical waveguide 204, it is difficult to increase the coupling efficiency for all of the plurality of laser diodes 202.

On the other hand, by forming the groove 501 in the optical waveguide 204, the optimum wavelength dependence of Δs can be reduced. FIG. 12 is a top view of the optical waveguide 204 and the laser diode 202 in this case. As shown in FIG. 12, the optical waveguide 204 has a groove 501 formed along the signal transmission direction. For example, the width of the groove 501 is 0.6a. Further, the depth of the groove 501 is, for example, about the same as the hole or deeper than the hole.

FIG. 13 is a diagram showing a simulation result of the coupling efficiency with respect to Δs / a in this case. As shown in FIG. 13, by forming the groove 501, the optimum wavelength dependence of Δs can be reduced. Thereby, the optimum Δs can be set for a plurality of laser diodes 202 having different wavelengths.

The method of shifting the pores by Δs and the method of providing the groove 501 can also be applied to the optical waveguide 203 connected to the photodiode 201.

Although the optical integrated circuit and the integrated circuit according to the embodiment of the present invention have been described above, the present disclosure is not limited to this embodiment.

For example, in the above description, the laser diode 202 and the photodiode 201 both include the sub-resonator 402, but only one of them may include the sub-resonator 402. Similarly, the characteristic configuration of the present disclosure described above may be applied to only one of the laser diode 202 and the photodiode 201.

Further, in the above description, the example in which the plurality of laser diodes 202 and the plurality of photodiodes 201 are alternately arranged above and below the optical waveguide 204 or 203 has been described, but the plurality of laser diodes 202 and the plurality of photodiodes 201 have been described. The arrangement of is not limited to this. For example, the plurality of laser diodes 202 and the plurality of photodiodes 201 may be arranged in the same direction of the optical waveguide 204 or 203.

In addition, the numbers used above are all examples for the purpose of specifically explaining the present disclosure, and the present disclosure is not limited to the illustrated numbers.

The optical integrated circuit and the integrated circuit according to one or more aspects have been described above based on the embodiment, but the present disclosure is not limited to this embodiment. As long as the gist of the present disclosure is not deviated, various modifications that can be conceived by those skilled in the art are applied to the present embodiment, and a form constructed by combining components in different embodiments is also within the scope of one or more embodiments. May be included within.

The present disclosure is applicable to optical integrated circuits and optical modules, and in particular, is applicable to optical integrated circuits and optical modules for wavelength division multiplexing transmission in optical communication.

100 Integrated Circuit 101 Block 102 Core 103 Port 104 Optical Integrated Circuit 105, 203, 204 Optical Waveguide 106 Optical Fiber 201, 201a, 201b, 201c Photodiode 202, 202a, 202b, 202c Laser Diode 205 Semiconductor Substrate 206, 303 Electrode 208 Input Light Signal 209 Output optical signal 301 Board 302 IC
304 Wiring 401, 401a, 401b Main resonator 402, 402a, 402b Sub-resonator 403 region 501 groove

Claims (11)

Optical waveguide and
Light formed on the side of the optical waveguide, which converts an electric signal into an optical signal and outputs the optical signal to the optical waveguide, or converts an optical signal transmitted through the optical waveguide into an electric signal. Equipped with a diode
The photodiode is
A circular main resonator surrounded by a photonic crystal structure,
An optical integrated circuit having a sub-resonator formed in the vicinity of the main resonator and surrounded by a photonic crystal structure. The optical integrated circuit according to claim 1, wherein the sub-resonator is formed asymmetrically with respect to a clockwise and counter-clockwise optical signals in the main resonator. The optical integrated circuit according to claim 1 or 2, wherein the sub-resonator has different effects on a clockwise optical signal and a counterclockwise optical signal in the main resonator. The optical integrated circuit according to any one of claims 1 to 3, wherein the sub-resonator is formed other than between the main resonator and the optical waveguide. The optical integrated circuit according to any one of claims 1 to 4, wherein the main resonator and the sub-resonator are adjacent to each other. The optical integrated circuit according to any one of claims 1 to 5, wherein the sub-resonator is formed by removing holes having a photonic crystal structure of 1 or more and 3 or less. The optical waveguide is surrounded on both sides by a photonic crystal structure.
The optical integrated circuit according to any one of claims 1 to 6, wherein the distance between the photonic crystal structures on both sides of the optical waveguide is wider than the distance between the photonic crystal structures on both sides of the optical waveguide. The optical integrated circuit includes a plurality of photodiodes including the light diode.
The plurality of optical diodes are formed on the side of the optical waveguide, and (1) convert an electric signal into an optical signal having different wavelengths from each other, and output the optical signal to the optical waveguide, or ( 2) Converting optical signals having different wavelengths transmitted through the optical waveguide into electrical signals,
The optical integrated circuit according to any one of claims 1 to 7, wherein the optical waveguide has a groove formed along a signal transmission direction. An integrated circuit that transmits signals via electricity and light.
An integrated circuit comprising the optical integrated circuit according to any one of claims 1 to 8. With multiple cores
An integrated circuit including the optical integrated circuit according to any one of claims 1 to 8, which transmits a signal between the plurality of cores. The integrated circuit includes a plurality of blocks, each containing a plurality of the cores.
The integrated circuit according to claim 10, wherein the optical integrated circuit transmits signals between the plurality of blocks.

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